Nephrology · Medical Literature
Impact of Blood Flow Rate and Duration of Dialysis Session on Nutritional Status in Hemodialysis Patients.
Abstract
Background. Chronic kidney disease (CKD) was commonly associated with malnutrition, with many patients exhibiting protein-energy deficiency and muscle wasting. Increasing blood flow rate (BFR) and extending dialysis duration had been considered strategies to improve nutritional outcomes in CKD stage 5 patients on maintenance hemodialysis. Aim. The study aimed to evaluate the effect of increased BFR and prolonged dialysis duration on the nutritional status of CKD stage 5 patients undergoing maintenance hemodialysis. Materials and Methods. This prospective randomized controlled study was conducted from 1st August to 1st October 2023 in a tertiary care centre. Ninety patients were randomized into three groups: Group 1 received BFR 250-300 mL/min for 4 hours; Group 2 received the same BFR for 5 hours; and Group 3 received BFR 300-350 mL/min for 4 hours. Nutritional assessments included serum albumin, BMI, Subjective Global Assessment (SGA), mid-arm muscle circumference (MAMC), triceps skinfold thickness (TSFT), and body composition monitoring (BCM), performed at baseline and after 3 months. Results. Significant improvements in SGA were observed between Group 1 and Group 2 (p = 0.035) and between Group 1 and Group 3 (p = 0.018). BCM also showed significant variation between Group 1 and both intervention groups (p = 0.015). No significant differences were found in MAMC, TSFT, or albumin categories. Group 2 demonstrated improvements in SGA, BCM, and urea, while Group 3 showed improvements in SGA, BCM, urea, and serum albumin. Conclusion. Increased BFR and longer dialysis duration positively influenced nutritional status, with higher BFR demonstrating the most notable benefit.
Clinical relevance
In CKD stage 5 patients on maintenance hemodialysis, does increasing blood flow rate (300–350 mL/min) or extending dialysis session duration (5 hours at 250–300 mL/min) improve nutritional status compared with standard hemodialysis (250–300 mL/min for 4 hours) over a 3-month period? __SNAPSHOT__ {"studyDesign":"Prospective randomized controlled trial, three-arm parallel group","setting":"Single tertiary care centre (country not reported in abstract); study period August 1 – October 1, 2023","sampleSize":"n = 90 (Group 1: n = 30, Group 2: n = 30, Group 3: n = 30)","population":"CKD stage 5 patients on maintenance hemodialysis; detailed inclusion/exclusion criteria not reported in abstract","intervention":"Group 2: BFR 250–300 mL/min for 5 hours (extended duration); Group 3: BFR 300–350 mL/min for 4 hours (higher BFR)","comparator":"Group 1 (control): BFR 250–300 mL/min for 4 hours (standard care)","primaryOutcome":"Not explicitly designated as a single primary endpoint; nutritional outcomes assessed included Subjective Global Assessment (SGA), serum albumin, BMI, mid-arm muscle circumference (MAMC), triceps skinfold thickness (TSFT), and body composition monitoring (BCM)","followUp":"3 months","fundingSource":"Not reported"}
Key findings
Statistically significant improvements in SGA were observed between Group 1 (standard) and Group 2 (extended duration; p = 0.035) and between Group 1 and Group 3 (higher BFR; p = 0.018). BCM showed significant variation between Group 1 and both intervention groups (p = 0.015). No significant differences were detected in MAMC, TSFT, or albumin categories across groups. On within-group analysis, Group 2 demonstrated improvements in SGA, BCM, and urea, while Group 3 showed improvements in SGA, BCM, urea, and serum albumin — suggesting a broader nutritional signal with higher BFR. Absolute effect sizes, confidence intervals, NNT, and between-group differences for continuous variables were not reported in the abstract. No safety or adverse event data were reported.
Practice implications
This small single-centre RCT suggests that both extending dialysis session duration (to 5 hours) and increasing BFR (to 300–350 mL/min) may modestly improve selected markers of nutritional status — particularly SGA and BCM — over 3 months in maintenance hemodialysis patients compared with a standard 4-hour/250–300 mL/min regimen. The higher-BFR group (Group 3) additionally showed improvement in serum albumin, which the extended-duration group (Group 2) did not, raising a hypothesis that BFR intensification may confer incremental nutritional benefit. However, these conclusions must be interpreted with significant caution: (1) only the abstract was available for review; (2) no primary endpoint was pre-specified, raising the risk of multiple comparisons and outcome reporting bias; (3) absolute effect sizes and confidence intervals are not reported, making clinical magnitude indeterminate; (4) MAMC, TSFT, and albumin categories did not reach significance between groups, limiting the breadth of the nutritional signal; (5) the study enrolled only 30 patients per arm, which is likely underpowered to detect differences in most nutritional endpoints; (6) follow-up was only 3 months; and (7) hard clinical outcomes (mortality, hospitalisation, quality of life) were not assessed. These results are hypothesis-generating and insufficient to change current practice. Patients outside CKD stage 5 on maintenance HD were not represented. __LIMITATIONS__ Only the abstract was available; full methodology, statistical analysis plan, and results tables could not be reviewed.,No pre-specified primary outcome; multiple nutritional endpoints tested simultaneously increase Type I error risk.,Small sample size (n = 30 per arm) likely underpowered for most nutritional endpoints; no power calculation reported.,Short 3-month follow-up is insufficient to assess durability of nutritional changes or clinically meaningful outcomes (mortality, hospitalisations, quality of life).,Single tertiary centre design limits generalisability to other practice settings, countries, and HD populations.,Absolute effect sizes, confidence intervals, and NNT/NNH not reported — statistical significance does not establish clinical importance.,Blinding of patients and assessors to dialysis prescription parameters is inherently difficult in this design; risk of performance and detection bias not addressed.,Baseline patient characteristics, comorbidities, dialysis vintage, vascular access type, and dialyzer specifications not described in abstract.,Funding source not reported; potential conflicts of interest unknown.,No safety data reported (e.g., haemodynamic instability, access-related complications at higher BFR, patient tolerance of extended sessions). __BOTTOM_LINE_CATEGORY__ promising_but_preliminary __BOTTOM_LINE__ This small 3-month RCT (n = 90) found statistically significant improvements in SGA and BCM with both extended dialysis duration (5 hours) and higher BFR (300–350 mL/min) compared with standard hemodialysis prescription, with the higher-BFR group also showing improvement in serum albumin. Absolute effect sizes and confidence intervals were not reported, the study was likely underpowered, and hard clinical outcomes were not assessed. These findings are hypothesis-generating only; adequately powered multicentre trials with pre-specified endpoints and longer follow-up are needed before practice modification can be considered.